Portable panels wire size

AStinker- wrote:
But isn't the input voltage still important somehow? If not why are we worried about voltage drop from the panels to the controller?

With MPPT the drop is important because this converts into lost amps and amp-hours.

With PWM - people more familiar with these low-tech devices ;) will correct me if I'm wrong - the voltage drop is not important as long as it is not lower than the highest Absorption voltage that you might need, i.e. Absorption on a cold day. As noted, and I agree, that it should also not be higher than 15V on a cold day.

So 15V is your lower limit of input after voltage drop at 77F. If it's lower, the controller with temp-comp won't be able to raise it as needed on a cold day. Controller with temp-comp will be able to lower it down from 15 on a hot day.

OTH, your controller should have means to limit maximum output to 15V - maybe it already has it as factory-preset. My controller has adjustable upper voltage.